<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // boolean --> number
        var b = true
        var f = false
        console.log(Number(b))  // 1
        console.log(Number(f))  // 0
    </script>
</body>
</html>